This invention seeks to improve a housing cover to be secured to a housing, particularly a crankcase of an internal combustion engine for an automotive vehicle. The conventional housing cover has a central opening through which a shaft, such as the engine crankshaft, may pass. The opening has an axis which is oriented perpendicularly to the plane of the central opening. The housing cover is of the type that is made of a drawn sheet metal body which is generally dish-shaped and which has axially offset radial surfaces. The bottom plate of the sheet metal body has bore holes for the passage of securing bolts. The bottom plate contains a first radial surface. A second radial surface of the housing cover is radially spaced from and is axially offset relative to the first surface and serves for receiving a static sealing strip which may be vulcanized thereto. The housing cover further supports a circular lip seal which bounds the central opening and which serves for sealing the shaft.
German Patent No. 3,634,735, to which corresponds U.S. Pat. No. 4,928,980, discloses a housing cover of the above-outlined type. The housing cover is made of a drawn sheet metal body which is essentially dish-shaped and has three radial surfaces disposed in different axial planes and which are at a stepped relationship to one another. The static seal is disposed on the second radial surface and is vulcanized thereto. In the installed state the dish-shaped sheet metal housing cover is, with its radial face that constitutes a bottom face, tightened against the housing with the aid of bolts passing through bore holes.
The elastomer sealing strip engaging the second radial surface of the known housing cover axially projects therefrom in the non-installed, separated state such that it extends beyond the first radial surface of the cover body. Upon tightening the housing cover the sealing strip is axially pressed against the housing to be sealed. In the cover body a free space has to be provided into which the elastomer material which, in itself, is incompressible, may yield. Such a free space is obtained by the step-like offset of the first and second radial surfaces and thus the sealing strip may expand radially inwardly. By virtue of this construction the first radial surface (bottom surface) may be firmly bolted to the housing without damaging or destroying the static seal.
It is a disadvantage of the conventional housing cover described above that upon installation thereof care has to be taken that the head of the securing bolt has a planar seat, that is, the bolt head must not lie on the transition zone between the first and the second radial surfaces because in such a case the transitional region is deformed by the tightening, whereupon the volume of the free space necessary for accommodating the yielding elastomer material is reduced. To avoid such a reduction in volume, the bore holes provided in the housing cover must be radially outwardly displaced to such an extent that the standard bolt does not contact, with the underface of the bolt head, the transitional zone leading to the second radial surface. It has been found, however, that in numerous internal combustion engines the space for installation is not sufficiently large to admit a housing cover in which the bolt openings (bore holes) are provided relatively far out in the radial direction, that is, relatively close to the peripheral edge of the housing cover.